ML19087A330

LLC Supplemental Response to NRC Request for Additional Information No. 185 (Erai No. 8963) on the NuScale Design Certification Application

ML19087A330
Person / Time
Site:	NuScale
Issue date:	03/28/2019
From:	Rad Z NuScale
To:	Document Control Desk, Office of New Reactors
References
RAIO-0319-65008
Download: ML19087A330 (7)

Text

RAIO-0319-65008 March 28, 2019 Docket No.52-048 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852-2738

SUBJECT:

NuScale Power, LLC Supplemental Response to NRC Request for Additional Information No. 185 (eRAI No. 8963) on the NuScale Design Certification Application

REFERENCES:

1. U.S. Nuclear Regulatory Commission, "Request for Additional Information No. 185 (eRAI No. 8963)," dated August 18, 2017

2. NuScale Power, LLC Response to NRC "Request for Additional Information No. 185 (eRAI No.8963)," dated December 20, 2018 The purpose of this letter is to provide the NuScale Power, LLC (NuScale) supplemental response to the referenced NRC Request for Additional Information (RAI).

The Enclosure to this letter contains NuScale's supplemental response to the following RAI Question from NRC eRAI No. 8963:

03.08.05-6 This letter and the enclosed response make no new regulatory commitments and no revisions to any existing regulatory commitments.

If you have any questions on this response, please contact Marty Bryan at 541-452-7172 or at mbryan@nuscalepower.com.

Sincerely, Zackary W. Rad Director, Regulatory Affairs NuScale Power, LLC Distribution: Gregory Cranston, NRC, OWFN-8H12 Samuel Lee, NRC, OWFN-8H12 Marieliz Vera, NRC, OWFN-8H12 : NuScale Supplemental Response to NRC Request for Additional Information eRAI No. 8963 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com

RAIO-0319-65008 :

NuScale Supplemental Response to NRC Request for Additional Information eRAI No. 8963 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com

Response to Request for Additional Information Docket No.52-048 eRAI No.: 8963 Date of RAI Issue: 08/18/2017 NRC Question No.: 03.08.05-6 10 CFR Part 50, Appendix A, GDC 1, 2, 4 and 5 provide the regulatory requirements for the design of the seismic Category I structures. DSRS Section 3.8.5 provides review guidance pertaining to the design and analysis procedures of foundations.

In FSAR Tier 2, Section 3.8.4.1, Description of Foundations, the applicant describes the basemat reinforcement pattern of the foundation of RXB, and in Tier 2, Appendix 3B Design Reports and Critical Section Details. However, the applicant did not provide sufficient information for the design assessments, boundary conditions for each foundation model, settlement evaluation and associated figures. Based on the review, the staff was not able to find sufficient information in the FSAR to make a safety assessment for the design of RXB basemat.

Therefore, provide the following information for the RXB basemat:

design assessments-should include: the capacity of sections, forces & moments at critical locations, design checks, etc.

boundary conditions for each foundation model -should include: stiffness types and parameter throughout the embedded portion of the RXB for each type of model (standalone and combined)

- SASSI2010, SAP2000, and ANSYS -- it should also be noted that, DSRS Section 3.8.5.II.4.N states In the case of gravity loads and basemat foundations, the soil stiffness parameters should be consistent with: (a) dishing or Boussinesq effects (if uncoupled distributed springs are used then it may be necessary for the stiffness to be increased at the edges and reduced at the center of the basemat footprint); (b) basemat size (subgrade modulus could be highly dependent on basemat dimensions); (c) time scale of the loads (i.e., short term construction loads vs. long term loads present throughout the life of the structure); and (d) soil type (i.e., granular vs. cohesive soils).

NuScale Nonproprietary

settlement evaluations and figures showing reinforcement patters for (a) the entire RXB basemat, (b) intersections between walls & the RXB basemat, and (c) intersections between pilasters & the RXB basemat. Settlement evaluation should include following types of settlements: (1) Maximum vertical settlements, (2) tilt settlement, (3) differential settlement between structures and (4) angular distortion.

NuScale Response:

Staff Feedback:

In DCA Part 2 Tier 2, DRAFT Revision 3, Section 3.8.5.1 Description of Foundations, the applicant changed the description of some of the reinforcing bars to headed reinforcing bars from reinforcing bars with standard hooks. The staff was not able to determine the applicability of headed reinforcing bars in ACI 349-06 (e.g.; Chapter 7 - Details of Reinforcement).

Therefore, the staff is requesting the applicant to provide the code and provision(s) justifying the use of headed reinforcing bars.

NuScale Response:

NuScale has chosen to use headed bars for shear reinforcement in slabs and walls, as needed, to eliminate congestion due to high bar density. Headed bars were introduced in ACI 318 in the 2008 edition, followed by ACI 349-13. Headed bars offer equivalent or superior performance compared to traditional bars. The use of headed bars offers less congestion, which facilitates concrete consolidation and faster installation times, reducing placement costs.

Two definitions of headed bars are included in ACI 318-08: headed deformed bars and headed shear stud reinforcement. Headed deformed bars are deformed reinforcing bars with a head attached at one or both ends conforming to ASTM A970/A970M. Headed shear stud reinforcement consists of individual headed studs, or groups of studs, with anchorage provided by a head at each end or by a common base rail consisting of a steel plate or shape conforming to ASTM A1044/A1044M.

Section 11.11.3 of ACI 318-08 allows the use of shear reinforcement for slabs and footings in the form of bars, as in the vertical legs of stirrups. ACI 318 emphasizes the importance of anchorage details and accurate placement of the shear reinforcement, especially in thin slabs.

Section 11.11.5 of ACI 318-08 permits headed shear stud reinforcement. A general procedure for evaluation of the punching shear strength of slab-column connections is given in Section 11.11 of ACI 318-08. Compared with a leg of a stirrup having bends at the ends, a stud head NuScale Nonproprietary

exhibits smaller slip, which results in smaller shear crack widths. This improved performance results in larger limits for shear strength and spacing between peripheral lines of headed shear stud reinforcement.

References

1. American Concrete Institute, "Building Code Requirements for Structural Concrete and Commentary," ACI 318-08, Farmington Hills, MI.

2. American Concrete Institute, "Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary," ACI 349-06, Farmington Hills, MI.

Impact on DCA:

FSAR Tier 2, Appendices 3B.1.1.3 and 3B.4 have been revised as described in the response above and as shown in the markup provided in this response.

NuScale Nonproprietary

NuScale Final Safety Analysis Report Design Reports and Critical Section Details S yy V C,YZ = 2 1 + -------------------- f' c b w d Eq. 3B-29 2000A g Capacity of concrete for elements subjected to axial tension (Syy is negative):

S yy V C,YZ = 2 1 + ----------------- f' c b w d Eq. 3B-30 500A g Out-of-plane shear D/C ratio:

V YZ D C YZ = ----------------------------------

- Eq. 3B-31 V C,YZ + V S RAI 03.08.05-6S1 Headed bars were introduced in ACI 318-08 (Reference 3B-9), followed by ACI 349-

13. Section 11.11.3 of ACI 318-08 allows the use of shear reinforcement for slabs and footings in the form of bars, as in the vertical legs of stirrups. Section 11.11.5 of ACI 318-08 permits headed shear stud reinforcement. Compared with a leg of a stirrup having bends at the ends, a stud head exhibits smaller slip, resulting in smaller shear crack widths. This improved performance results in larger limits for shear strength and spacing between peripheral lines of headed shear stud reinforcement. Therefore, the design may use headed bars for shear reinforcement in slabs and walls, as needed, to eliminate congestion due to high bar density.

3B.1.1.4 Basemat Foundation Design Force and Moments The design check considers bounding demand forces and moments for the basemat.

The demand forces and moments of the design check consist of:

• Out-of-plane moment, in kip-ft per unit length in feet: maximum out-of-plane moment in either of the two perpendicular directions in-plane

• Out-of-plane shear force, in kips per unit length in feet: maximum out-of-plane shear force from either of the planes XZ or YZ

• In-plane shear force, in kips per unit length in feet: maximum in-plane shear force

• Axial force along x- or y-direction in kips per unit length in feet: maximum axial tension along the x- or y-axis The SASSI2010 program calculates the dynamic stresses due to a seismic excitation at the centroid of a solid element. These stresses are post-processed to obtain the forces and bending moments in the basemat foundation. The dynamic forces and moments in a solid element are combined with the corresponding static forces and Tier 2 3B-12 Draft Revision 3

NuScale Final Safety Analysis Report Design Reports and Critical Section Details 3B-6 NuScale Power, LLC, "NuScale Power Module Seismic Analysis," TR-0916-51502.

RAI 03.08.04-13 3B-7 American Society of Mechanical Engineers, Boiler and Pressure Vessel Code, 2013 Edition No Addenda,Section III, Rules for Construction of Nuclear Facility Components and applicable addenda, New York, NY.

RAI 03.08.04-13 3B-8 American Concrete Institute, Reinforced Concrete Design for Thermal Effects on Nuclear Power Plant Structures, ACI 349.1R-07, Farmington Hills, MI.

RAI 03.08.05-6S1 3B-9 American Concrete Institute, "Building Code Requirements for Structural Concrete and Commentary," ACI 318-08, Farmington Hills, MI.

Tier 2 3B-40 Draft Revision 3